It is frequently necessary to close an opening in a tubular member either temporarily, semi-permanently or, in the case of the present invention, permanently. That is, to close an opening when a valve is not required and is not desirable. One example of the utilization of a completion plug arises when a hot tap is made into a pipeline or vessel through a fitting connected to the pipeline or vessel. In the typical hot tapping application as utilized in the petroleum, chemical, refinery and other similar industries, a fitting, usually in the form of a flange, is welded on the exterior of a pipe that has flowing gas or liquid under pressure. A valve is then secured to the flange and a hot tapping machine is secured to the valve. By use of specialized equipment, a hole can then be drilled through the wall of the pipe while gas or liquid continues to flow through it. This provides access to the interior of the pipe, such as for inserting equipment to temporary block flow through the pipe while repairs are being made. After repairs are complete, the equipment is removed and the opening that provides communication to the interior of the pipe needs to be closed. In some instances, as above indicated, the closure is made in a way that at a future date access can again be obtained through the fitting to the interior of the pipe. In the present case a completion plug is provided that permanently closes the opening. In addition, most known completion plugs make use of elastomers, such as rubber or plastics, to achieve leak proof sealing. The present invention, in contrast, provides heat resisting, metal-to-metal sealing.
For background information relating to completion plugs, reference may be had to the following previously issued United States patents.
PatentNumberInventorTitle428,422SkinnerCasing Head1,810,621ParksValve Mechanism2,085,119Penick et al.Seal Off Tool2,134,311Minor et al.Method and Apparatus For Suspendingand Sealing Well Casings2,771,096Ver NooyFluid Tight Closure2,988,111Ver NooyFluid Tight Closure3,074,591RaverPressure Closure3,155,116Ver NooyApparatus For Closing Side OpeningsInto Pipelines3,289,765HynesMethod and Apparatus For CompletingWells3,405,763Pitts et al.Well Completion Apparatus and Method3,766,947OsburnFluid Tight Closure4,058,142RankinPipeline Fitting4,144,909HarrisonApparatus For Closing Side OpeningsInto Pipelines4,326,587Gauthier et al.Casing Hanger and StabilizerApparatus and Method4,387,740VanzantCam-Flange4,466,550SullivanClosure For A Cylindrical OpeningHaving Improved Venting Means4,609,209RallsPrecise Alignment Adapter Flange4,693,278Wilson et al.Safety Closure Member4,749,047TaylorAnnular Wellhead Seal4,886,121Demny et al.Universal Flexbowl Wellheadand Well Completion Method5,114,158LePacking Assembly For OilfieldEquipment and Method5,209,521OsborneExpanding Load Shoulder5,327,965Stephan et al.Wellhead Completion System5,450,765StoverApparatus For Providing SignalCommunication Between The Interior andExterior Of A Pipeline5,456,320BakerCasing Seal and Spool For Use InFracturing Wells5,490,565BakerCasing Seal and Spool For Use InFracturing Wells5,975,142WilsonRemovable Closure System5,984,008Lang et al.Installable Load Shoulder For Use In AWellhead To Support A Tubing Hanger6,116,285WilsonRemovable Threaded Plug6,286,553MorganRemovable Closure System